Spermicides are one of a number of contraceptive methods known in the prior art. The most popular spermicide contains Nonoxynol-9 (N9) as the active ingredient. However, N9 does not provide the user with protection against sexually transmitted infections (STIs), such as Human Immunodeficiency Virus (HIV), Herpes simplex virus (HSV) and other viral and microbial pathogens. In fact, N9, which is a detergent based spermicide, may actually have adverse effects in the prevention of STIs. Whilst such detergents act to disrupt HIV and HSV membranes, they may also compromise the natural vaginal barrier and significantly increase susceptibility to infection.
International patent application no PCT/AU02/00407 (WO 02/079299), to applicants, the entire contents of which are incorporated herein by reference, discloses a class of dendrimers (highly branched macromolecules with a defined envelope of polyanionic or cationic surface groups) which have been shown to exhibit a range of antiviral and antimicrobial activity with minimal toxicity.
For example, polylysine, polyamidoamine (PAMAM), poly(etherhydroxylamine) (PEHAM) and polypropyleneimine dendrimers including the compounds represented by Formulae I to III below and bearing naphthyl disulphonic acid surface groups, have been shown to exhibit antimicrobial activity, particularly antiviral activity.
where R represents a group of the Formula IV:

It would accordingly be a significant advance in the art if a contraceptive compound could be provided as an alternative to the spermicides including N9 currently known in the art, which does not have adverse effects in the prevention or transmission of STIs.